Plural coated waterproof support



United States Patent '0 PLURAL COATED WATERPROOF SUPPORT.

Pierre Demol, Brussels, and Pierre Mathis, Schaerbeek,

' Belgium, assignorsto Solvay&Cie',,Br'ussels, Belgium 7 --No Drawing. Filed May- 6, 1966, Ser. No. 548,066

Claims priority, applicgtion lgelgium, May 19, 1965,

Int. (:1. B44il 1/14, /0

U.S. Cl.11776 V a 10 Claims The present invention relates to various types of supports which arerendered waterproof with the aid of a polymeric coating and more particularly to-a novel process of waterproofing and to such" supports rendered water: proof bythe employment of a coating of two or more copolymers of vinylidene chloride. 1

It is well knownvthat copolymers having a baseof vinylidene chloride have been used for coating. various supports, i.e., paper; cardboard, leather, etc.," in order to render them water-proof. These copolymers are generally prepared by polymerization in an aqueous emulsion. Although the coating operation canbe performed starting with organicsolutions of the copolymers, for economic reasons, it has been preferred to start with aqueous emulsions. Inf such a process, it is' not absolutely necessary to separate. the copolymer from the polymerization medium and thus the problem of the recovery of a solvent need not arise.

Numerous "copolymers of vinylidene chloride have already been proposed'andusedforthe coating of various supports from'aqueous emulsions-However, none of the known copolymers, considered individually, has been capable to confer to the support an impermeability to water vapor, gas and greases which is at the same time sufiiciently high and durable. 1 a

In accordance'with the present invention, however, it has now been found'that acoating for supports which confers to su'chsupports a high impermeability to water, water vapor, -gases,'. greases, oils, etc., such high impermeability being retained after manipulation; can be produced by employing at least 2 copolymers of vinylidene chloride, which copolymers have difierent'compositions and natures.

' a It is therefore a principal obiectof the present invention to provide waterproofed supports, and a process for producing such supports which are free from the inherent deficiencies of. "previously employed materials.

Still a further object of the -present, invention comprises a coating for supports which confers to such supports, a high impermeability to water, water vapor, gases, greases, oils, etc. such high impermeability having great durability W It i yet a further object of the present invention to coat supports in which the waterproof coating'comprises at Ie'a'sttW-d" copolymers ofvinylidene chloride; suclr-co= polymers Hifiering in composition and nature. "1 1 A still further object of the present invention is to pro- .vide such coated supports wherein the coating comprises .a combination of fsupple and hard copolymers of vinylidene chloride. 1

Still iurther objects and advantages of the present invention -will--become more apparentfromtheafollow-ing more detailed description of the invention.

"ice

By selecting several copolymersof vinylidene chloride which have different compositions and natures, and by combining them, it has now been found that it is possible to prepare coated supports possessing an increased initial impermeability to liquids, gases, etc., which is retained to an extremely acceptable degree after manipulation.

In general, any support capable of being rendered impermeable to liquids, gases, etc., by coating with a synthetic plastic can be advantageously treated in accordance with the present invention. Suitable, non-limitative, exam ples include paper, cardboard, pasteboard, plywood and other wood products, leather (both natural and artificial), fabrics (knitted, woven, etc), rubber, cellophane and various thermosetting and thermoplastic resinous materials. t

H The present invention is thus directed to such suitable supports which are rendered waterproof, etc., with the aid of a coating which has as a base two or more copolymers of vinylidene chloride, such coating being preferably applied from aqueous emulsions. The coated supports are further characterized in that atleast one copolymer of vinylidene chloride is chosen from among the supple copolymers and at least one other is chosen from among those copolymers characterized as hard.

The copolymers of vinylidene chloride which are exemplified as hard are characterized by a very high concentration of vinylidene chloride. The weight ratio be-. tween vinylidene chloride and the other comonomer or comonomers is between 4 and 49. The suitable comonomers are chosen from among acrylonitrile, methacrylonitrile and the esters derived from unsaturated monoor polycarboxylic acids and saturated alcohols containing a maximum of 4 carbon atoms. Among the above-men: tioned esters, acrylates, methacrylates, itaconatesand alkyl fumarates of the C -C type are preferred.

These copolymers identified as hard, when employed alone, give the support an initially high impermeability, but the coating is hard and brittle and does not resist the folding or rubbing of the coated support. If employed alone, therefore, a substantial decrease in the impermeability results.

Among the copolymers which are characterized as supple, it is preferred to use the internally plasticized copolymers of vinylidene chloride and vinyl chloride in which the vinylidene chloride/vinyl chloride weight ratio is between 0.6 and 4and the plasticizing comonomer or comonomers, which are present in a concentration of 1-100 grams per kilogram, preferably 5-S0 grams p'er'kil'o'gram', are chosen from among the esters of unsaturated monoor polycarboxylic acids and saturated alcohols containing 4 to 18 carbon atoms, the vinyl esters of saturated carboxylic acids containing 6 to 18 carbon atoms, and mixtures of these. Among the esters of the first type, acrylates, methacrylates, itaconates and alkyl fumarates of the C -C for example ethylhexyl, are preferred. Vinyl stearate and vinyl ,laurate are exemplary of the vinyl carboxylates useful herein.

Supports coated only by means of copolymers identified as supple present a poor initial impermeability in comparison with supports coated by means of one of resistant to manipulation.

By utilizing at the same time hard copolymers and supple copolymers for coating the same support, it

has now been found that it is possible to avoid to a large extent the defects of the two types of copolymers while at the same time conserving their distinct advantages. I

The hard and supple copolymers utilized in the present invention can also contain components derived from other monomersf9r the purpose of improving certain properties of the coatings. Thus, for the purpose of giving the coating a suitable adherence to the support, The composition of the various copolymers utilized is polymerization of a small amount of a holding (clinging) summarized in Table I below.

TABLE 1 Test No.

No. of Layers I Composition of copolymers 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 Vinylidene chloride, gr./Kgr 920 920 590 590 590 920 590 920 720 720 720 920 570 570 570 920 2 1 Methyl acrylate, gr./Kgr 80 80 80 80 80 8O Pi 88 "$331 38 V1nylchloride,gr./Kgr 380 380 380 380 220 220 220 380 380 380 380 380 Ethylhexyl acrylate, gr./Kgr 0 3 1 3 Ethylhexyl fumarate, gr./Kgr Vinyl stearate, gr./Kgr

Ethylhexyl itaconate, grJKg Lauryl methaerylate, gr./Kgr

At the time of the preparation of the copolymer the ethylhexyl acrylate was introduced in a delayed manner between the 7th and the 10th hour of the polymerization.

monomer such as acrylic acid, maleic anhydride, acryl- In all of the above-noted tests, the coating was efamide, or itaconic acid could be advantageously emfectuated by means of a machine equipped with an air ployed, sheet device for regulating the weight of the coating at Moreover, more stable emulsions of the various coa level of 20 grams per sq. meter for the first layer polymers can be obtained by effecting the polymerization and 10 grams per sq. meter for the second layer.

in the presence of a small quantity of a polymerizable After each passage, the coating was dried in a horicompound such as vinylsulfonic acid. zontal tunnel which was swept by an air current at 135 The various copolymers of the present invention c n C., and equipped with infra-red radiation emitting elebe prepared by any known polymerization process capable ments at its beginning and end.

of producing aqueousemulsions. One portion of the coated paper was subjected for The coating of the pp can be carried out in several forty-eight hours to a conditioning at 43% relative huways in accordance with the present invention. In order midity and 23 C.,.in such a manner as to give it a to simplify the operation, the aqueous emulsions of the water t t f7 to 8%, 1

ehOSeIl and pp copolymer of copolym rs The other portion was placed for 48 hours in a dryingy be mixed and coated on the pp in one of Several oven at 50 C. This treatment is used to illustrate ac layers. celerated ageing which results in complete evolution However, the best results with respect to impermeability i th crystallinity rate i of h coating may be obtained by sequentially applying to the sup- After this treatment, the aged, coated paper was subport at least one sub-layer of an aqueous emulsion of jected to the conditioning treatment set forth. one or more supple copolymers, with subsequent ap- On one portion of the aged and non-aged papers, a plication of at least one layer having a base of one r Severe rubbing abradi11g was effeetuated y y g Out more hard copolymers. a simultaneous translational and rotational movement,

The following examples illustrate various embodiments on a GELBO-TESTER PP of the present invention. It is to be understood that these on the four types of Samples Pr u ed, 1.6., non-aged, examples are presented for purposes of illustration only non'abradefi Paper; abraded non'aged Paper; non-abraqed and the invention is in no way to be deemed as limited aged Paper i abraded a paper tests were earned thereto out to determine the porosity to greases and the permeability to water vapor.

The porosity test carried out with respect to greases consisted of applying a layer of red colored essence of turpentine on the coated surface of the paper, and then covering it with a glass plate for preventing the evaporation of the turpentine. After 15 minutes, the number of Examples Various tests were carried out by applying two coating layers to kraft paper and the impermeability properties of the coated su ort determined.

Table I giv si the compositions of the copolymers plts Whlch g f f the lnoncoated 3 F i pager were counte an e resu ts expresse in e num er utilized for the different layers of the coatings used in the of pits found per Sq. meter. tests The permeability to water vapor was measured by The tests 5 and 7 are supphed for comharatlve the method described in ASTM E9653T standard, propurposes- In test the two layers of the coatmg are cedure E, tropical conditions (90% relative humidity and constituted y the Same copolymer of the type 37.8 C.). In the case of non-abraded paper, the samples While in tests 5 and 7 there is employed an aqueous were stretched over pans containing dehydrating agents,

emulsion of y one pp P Y while the samples of abraded paper were used for the 111 tests 9 and e sublayer is produced production, by thermo-sealing, of sachets containing the from an aqueous emulsion of a supple copolymer and dehydrating agent. the upper layer consists of a hard copolymer. The results obtained are shown in Table II.

TABLE II Test N0. Properties of coated paper 1 2 3 4 5 6 7 8 9 10 Porosity to greases, pits/m1:

N on-abraded, non-aged 0 20 0 0 120 8O 50 30 Non-abraded, aged 50 100 30 20 150 100 80 50 Abraded, non-aged 9, 700 5, 000 1, 500 1, 500 6, 000 3, 500 5, 500 2, 400 2, 000 2, 600 Abraded, aged 15, 000 5, 600 5, 000 4, 500 6, 900 7, 000 6, 800 6, 700 7, 000 7, 000

Permeability to water vapor, gin/m3:

N on-abraded, non-aged 9. 1 16 5 3. 4 17. 4 12. 6 16. 1 7. 6 4. 8 8. 9 Non-abraded, aged 10. 5 16. 2 6. 2 3.1 18. 9 13 1 16. 3 8. 7 5. 4 9. 3 Abraded, non-aged 27. 8 23. 7 8. 9 6. 9 26. 7 20 8 25. 6 11 9 10. 1 13. 5 Abraded, aged 75. 7 41. 7 25. 4 23. 1 58. 7 48 2 42 34 5 30. 5 88. 7

A comparison between the properties of coated papers considered in tests 1, 2, 5 and 7, provided for reference purposes, and the properties of the coated papers considered in the other tests permits a ready appreciation of the progress represented by the supports which were rendered impermeable according to the present invention. Thus, with respect to impermeability to greases, a greater number of pits were observed in the coating not in accordance with the present invention than were observed when the combined supple and hard coating of the present invention was employed. Similarly, with respect to impermeability of water vapor, the unusually advantageous properties of the combined coating of the present invention are easily observed.

It will be understood that the above description of the present invention is susceptible to various modifications, changes, and adaptations, and the same are intended to be comprehended within the meaning and range of equivalents.

What is claimed is:

1. A waterproof coated support comprising a substrate coated with at least one sublayer and at least one outer layer, each sublayer comprising a supple vinylidene chloride/vinyl chloride copolymer having a Weight ratio of vinylidene chloride to vinyl chloride between 0.6 and 4 and containing from 1 to 100 grams per kilogram derived from monomer having a plasticizing character and selected from the group consisting of (1) an ester derived from (a) an unsaturated monoor polycarboxylic acid and (b) a saturated alcohol containing from 4 to 18 carbon atoms, (2) a vinyl ester of a saturated carboxylic acid containing from 6 to 18 carbon atoms and (3) a mixture of esters selected from the group consisting of those defined in (1) and (2) and each outer layer comprising a hard vinylidene chloride copolymer in which the weight ratio of vinylidene chloride to copolymerizable monomer is between 4 and 49, the copolymerizable monomer comprising at least one member selected from the group consisting of (1) acrylonitrile, (2) methacrylonitrile and (3) an ester derived from (a) an unsaturated monoor polycarboxylic acid and (b) a saturated alcohol containing at most 4 carbon atoms.

2. A coated support according to claim 1 wherein the substrate is paper, cardboard, pasteboard or plywood.

3. A coated support according to claim 1 wherein the substrate is kraft paper.

4. A coated support according to claim 1, the monomer having a plasticising character being selected from the group consisting of (1) an acrylate, methacrylate, fumarate or itaconate of a saturated alcohol having from 4 to 18 carbon atoms, (2) vinyl stearate and (3) vinyl laurate and the copolymerizable monomer in the hard vinylidene chloride copolymer being selected from the group consisting of (1) acrylonitrile, (2) methacrylonitrile and (3) an acrylate, methacrylate, fumarate or itaconate of a saturated alcohol containing a maximum of four carbon atoms.

5. A coated support according to claim 1 wherein the hard vinylidene chloride copolymer is a vinylidene chloride methyl acrylate copolymer.

6. A coated support according to claim 1 wherein the supple copolymer is a vinylidene chloride/vinyl chloride/ethylhexyl acrylate terpolymer.

7. A coated support according to claim 1 wherein the supple copolymer is a vinylidene chloride/vinyl chloride/ethylhexyl fumarate terpolymer.

8. A coated support according to claim 1 wherein the supple copolymer is a vinylidene chloride/vanyl chloride/ vinyl stearate terpolymer.

9. A coated support according to claim 1 wherein the supple copolymer is a vinylidene chloride/vinyl chloride/ethylhexyl itaconate terpolymer.

10. A coated support according to claim 1 wherein the supple copolymer is a vinylidene chloride/vinyl chloride/lauryl methacrylate terpolymer.

References Cited UNITED STATES PATENTS 2,636,870 4/1953 Connors et a1. 117161 2,829,069 4/1958 Michel 1l7-l61 X 3,130,176 4/1964 Zdanowski et al. 11772 X 3,240,742 3/1966 Hahn et a1 260-2926 X 3,423,232 1/ 1969 Reinhard et a1.

WILLIAM D. MARTIN, Primary Examiner R. HUSACK, Assistant Examiner 

